The Canadian film-maker Allan King, who has died of brain cancer aged 79, was a master of the fly-on-the-wall genre of documentary, regardless of whether one calls it cinéma vérité, direct cinema or actuality drama. In fact, King favoured the last description for his films, which he made by shooting the drama of everyday life as spontaneously as possible without any direction of the participants, or interviews or narration, using lightweight hand-held cameras. "I strive to serve the action as unobtrusively as possible," King explained.

This method was achieved by his becoming extremely familiar with the environment and the people before filming, developing mutual trust. The results of this are no more apparent than in King's most celebrated documentary, Warrendale (1967), which won the Prix d'Art et d'Essai in Cannes, and shared the Bafta award for best foreign film with Antonioni's Blow Up. Warrendale, a shattering film, was initially made for the Canadian Broadcast Corporation (CBC), which refused to show it, not only because of the use of words forbidden on television at the time, but because of its uncompromising nature.

King and his small crew spent four weeks at Warrendale, a school for emotionally disturbed children outside Toronto before beginning eight weeks of shooting. In the school, the children are encouraged to release all their anger and aggression during "holding sessions," which involved being tightly held by two or three adult staff members. The most startling sequence shows the different reactions of the inmates to the sudden death of the school's cook. "It's a lie! It's a lie!" sobs one young girl, while another child blames herself. Despite King's objective, non-judgmental hands-off style, audiences of all ages, cannot help but identify with these children full of fear and grief.

Born and educated in Vancouver (he studied philosophy at the University of British Columbia), King got his first job at CBC in 1954. Two years later, aged 26, he made his first film for them, a medium-length documentary called Skid Row, which paved the way for other remarkable "actuality dramas" and was a prime example of what was to be known in Canada as the West Coast School of film-making. Taking advantage of the relatively low-cost "synch-sound" camera, King moved sympathetically among the homeless people of Vancouver, lending them some kind of dignity.

Soon after, King went to London, where he established Allan King Associates with the aim of producing documentaries for CBC about the world seen through Canadian eyes. The first was Rickshaw (1960), which revealed the harsh and unrewarding life of an ageing Calcutta rickshaw driver. After filming a superb interview (by Bernard Braden) of Orson Welles in his Paris apartment, King returned to Canada for A Matter of Pride (1961), in which he highlighted the pain of unemployment represented by a middle-aged salesman, told mostly through long interviews. Such was the effect of the film, which gave the lie to the idea of Canada as a booming economy, that it was discussed in parliament and denounced by the prime minister, John Diefenbaker.

After several more committed films for CBC, King made Warrendale as his first feature-length film. It placed him on a par with other practitioners of cinéma vérité such as Albert Maysles (from whom King borrowed his first camera), Richard Leacock and Fred Wiseman, though, curiously, the Canadian remained far less known internationally. This might be because the US has more publicity power but, more likely, because King's films are so unflinching in their observation of subjects most of us would rather ignore.

King followed the success of Warrendale with A Married Couple (1969), another feature, this time a docu-drama in colour. The film gets extremely up close and personal with Antoinette and Billy Edwards; she being a 30-year-old secretary and he a 42-year-old advertising executive, a couple suffering the seven-year itch. For 10 weeks, King and his crew (Richard Leiterman, the cameraman, and Christian Wangler, the soundman) more or less lived with the pair, recording almost 70 hours of footage, skilfully edited down to 97 minutes by Arla Saare.

"I'm completely bewildered," Billy says toward the end of the film. "It seems that every time we get on some plateau of understanding, the next minute we are kicking and screaming." King recognises that the couple, who really love each other despite the sometimes violent arguments, are playing to the camera to a certain extent, which nevertheless provides us with some kind of meta-truth.

King's ventures into fictional features were more conventional, though Who Has Seen the Wind (1977), about a young boy growing up on the prairies of Saskatchewan during the Depression, was touching and lyrical. During the 1980s and 90s, King worked almost exclusively on television series, making a good living directing episodes of Alfred Hitchcock Presents, Danger Bay, Dracula: the Series, Road to Avonlea, and Kung Fu: the Legend Continues.

Then, in the last decade of his life, King returned to the kind of vérité films that made his reputation, two of them concerning old age and death. In Dying at Grace (2003), King concentrated on the final days of five people, coming to terms with their demise, at the Salvation Army Toronto Grace health centre. "Self-interest is the reason I make most of my films," he said. "I'm getting older and I'm going to die. I thought I'd better find out what it's about."

Memory for Max, Claire, Ida and Company (2006), which deals with people in varying stages of Alzheimer's, is difficult to watch at times, but it is a poignant reminder of what has been lost as well as a memorial to a full life. In contrast, King's last film, EMPz 4 Life (2007), was about youth: four 13-year-old black boys, struggling against racism and despair in a Toronto suburb.

King, who received the Directors Guild of Canada's distinguished service award and the Arts Toronto lifetime achievement award, is survived by his third wife, Colleen, two sons, Sasha and August, and two daughters, Maggie and Anna.

Mike Dodds writes: Formed in 1961, Allan King Associates (AKA) in Soho quickly became known as one of the early adopters of the new lightweight and silent 16mm film cameras and portable sound recorders which required fewer crew members to operate. Allan gathered around him a group of young, talented freelance film-makers who were soon working together as a co-operative, hiring themselves and their new equipment to the BBC and the commercial broadcast channels. Monies earned went into a common pool and were used as needs dictated.

At the time, there was strong resistance to this new technology from the broadcasting technical departments, who viewed 16mm film and 1/4in recording tape as sub-standard and therefore non broadcastable. The film union ACTT, who feared that the new technology would have an impact on their traditional manning levels in the industry, were also resistant. However, AKA and a few other small independent film companies in and around Soho gradually changed the technical and cultural landscape of documentary film-making in the UK; a shift that both unions and broadcasters eventually acknowledged.

The Soho office became a base for freelance filmmakers and assorted arts and media people who could be seen to represent the creative powerhouse of London in the 1960s and 70s. It was no surprise to come in to the office in Broadwick Street to find the likes of Allen Ginsberg, John Lennon, Yoko Ono, Jonathan Miller or Kenneth Anger; some working on projects in the cutting rooms, others just hanging out, soaking up the creative buzz.

When Allan returned to Canada in the 1970s, the AKA he left behind in London struggled to find a new identity and eventually succumbed to economic factors in the early 1990s. Some of the associates and friends of AKA have made their own mark on the UK film industry, however, among them Roger Graef, Christian Wangler, Mark Peploe, Ivan Sharrock and Chris Menges. Allan King leaves a legacy that embraces an impressive personal portfolio of films but also an indelible stamp on the development of the documentary movement in the UK.

• Allan Winton King, film director, born 6 February 1930; died 15 June 2009